Clashing
by Honest Rebel
Summary: With their universes threatening to collapse, Finn and Fionna must work together to stop the force causing this apocalypse or find a safe place for their friends to escape to. Since they're the same person, that makes it easy to team up, right? Not exactly. See how the Adventure Time characters react to their doppelgangers...
1. Chapter 1: Shaky

My first fanfic. Dunno if I did it right or not.

I don't exactly understand why you have to disclain things even if this is clearly a fanfiction sight where no one is writing original peices, but will do any how since I would prefer to not be sued.

DISCLAIMER: I DO NOT OWN ADVENTURE TIME OR ANY OF ITS CHARACTERS. I JUST THINK IT'S RAD AND THIS COULD BE AN EPIC EPISODE. OR MAYBE EVEN A MOVIE.

Wait, I don't even know how to make a disclaimer. Was that good enough? Is someone going to report me? Will I be getting harassing phone calls from someone's lawyer? Do you want to read my story or what? Well scroll down and Read!

Chapter 1: Shaky

The ground jolted, throwing Finn off balance. Jake quickly stretched to save his friend from getting too friendly with the dirt.

"There it is again! What the math, dude?" Finn said, turning to his magical dog.

"Dunno. Maybe it's the fish people having a party. Ooh! we should go check it out! We haven't see Susan Strong in a while!" Jake said, easily distracted. Finn didn't forget about the weird land shakes, but decided that if they went underground, they might find the cause.

They reached the hatch that led to Beautopia, they knew they wouldn't be able to get down there, not this way.

"Oh my Glob." Jake said, his eyes widening. Nearly the entire field that was once taffy trees had collapsed into a monstrous crater.

"Dude, you don't think Susan and the fish people were down there, do you?" Finn asked, feeling suddenly panicked.

"Maybe. But they're probably okay." Jake assured. A large chunk of land crashed into the crater in the distance.

"I hope." He added quietly. Finn stood there a long time, staring into the yawning hole. He wanted to believe Jake. Even if they were down there, they probably would have been spooked by the earthquakes and been trying to get away from them. At that moment, another violent surge caught Finn off guard and sent him flailing down into the basin.

"JAAAAAAAAAAAAAAAAAAAKE!" He bellowed as the jagged bottom grew close. Jake snapped into action, jumping in after Finn, stretching his arms to secure him before expanding his body into a parachute form.

"I gotcha buddy." He said, as they floated gently to a somewhat even patch at the bottom.

"Yeah." Finn squeaked, gripping Jake's arms tightly. When they landed, Jake shrunk back into his natural form, chuckling.

"You were really freaked, huh?" he said.

"Not THAT freaked. I was just...surprised." Finn said self righteously.

"Yeah, whatever, you're just lucky Flame Princess doesn't know what a girly scream you have." Jake said roguishly.

"I DON'T SCREAM LIKE A GIRL!" Finn yelled, his voice breaking at the most inopportune time, making Jake roll around on the ground with laughter while Finn glared red-faced at him.

"Shut up Jake." Finn said.

"Hahahaha, 'I'm Finn and I scream like a girl'!" Jake said in a falsetto voice.

"I said shut up!" Finn hissed, trying to shut Jake out.

"It's cool bro, Jakey just likey making fun of your puberty!" Jake said, not getting it. Finn slapped his hand over Jake's mouth, listening hard.

"Be quiet!" he said. He thought he heard something other than his dog making fun of his squeaky voice. Jake mumbled behind his hand.

"Sh!" Finn shushed, letting go of him and walking toward the place he thought he heard the noise. There was faint moan to his right and Finn pounced on it.

"HELLO? CAN YOU HEAR ME? I HEARD YOU!" He called at the dirt. More barely perceptible murmurs.

"Jake! There's a voice under this mess!" he yelled over his shoulder, attacking the sod. Jake quickly stretched over.

"Oh yeah, man, I bet there's a body attached to that voice!" He said excitedly, helping. As they dug deeper, the voice got louder. At some point, Finn knew who it was and it made his hands go faster. Finally, a hand broke through.

"Susan!" Finn said, knowing he would recognize those meaty fingers anywhere.

"Stand back." Jake warned, squeezing his upper body down the small gap they had made and bringing Susan up.

"Susan! What happened? Where's the fish people?" Finn asked, crouching down next to her. He really didn't need to, she was almost taller that him sitting down too. She seemed to be holding herself like she was scared.

"Hey, it's okay, you're safe now." Finn said, patting her shoulder, brushing off some of the dirt. She didn't move.

"Oh, dude..." Jake said, staring.

"What?" Finn said cluelessly. Why was Jake gaping like that? He noticed that Susan Strong wasn't holding herself, there was something in her arms. Something that move and fussed. Susan had a baby with her.

So this is the part where I tell you that I messed up on this and that, but I think I did a pretty good job. With the story part at least. Yeah, the part with Fionna is going to come up, maybe not in the next chapter, but soon. I don't like to rush things. If you read this, thank you for giving my life meaning! ^.~


	2. Chapter 2: Worries

Chapter 2: Worries

Finn and Jake led Susan and to the Candy Kingdom, because Jake said that the baby might need special attention. Susan was unwilling to let them see the baby, she kept it cradled to her chest the entire walk to the Candy Kingdom. In fact, she was so absorbed that she didn't even look twice at all the candy of the Candy Kingdom, not even Peppermint Butler.

"Finn, are you sure it was...wise to bring her back here?" Princess Bubblegum whispered as they sat in the hospital waiting room.

"I don't know, Jake said we should. Besides, she's too distracted by that baby to eat anyone. What's the deal with that anyway? I didn't see any gills or fins on it." Finn said. PB sighed.

"Neither did I. Not that Susan was particularly generous with letting me see." she said a little crossly. Finn knew PB just wanted to do science-y stuff. He, on the other hand, was deeply intrigued. As a fourteen year old boy just beginning to learn about 'the birds and the bees' he knew for certain that it took a man and woman to make a baby. Jake had conveyed this much after Lady Rainicorn announced she was pregnant. Finn looked toward Jake, who was standing in the door where Susan was, just staring. He hadn't said much since they rescued Susan, his face was blank. Doctor Ice Cream came out of the room and heaved a sigh.

"It's no good. She won't even let us take the baby's temperature." she announced. Not a split second after that, rumbling that seemed to come from all around them began. It started low, like a mumble, then quickly progressing into a gut wrenching roar. Finn felt as though it were the very noise of fear itself, he couldn't tell if that was his spine tingling or the floor vibrating.

Princess Bubblegum wasn't used to being so off balanced or scared, she reflexively reached out for something to hold onto. That 'something' just happened to be Finn. She could hear the shrieks of the candy people both in the hospital and oustide in the streets. These earthquakes have been going on all day, but her science stuff didn't tell her anything except that the ground was shaking. This could be guessed by the simplest of the candy people and only made PB frustrated with her instruments.

Slowly, the shaking faded to a tremor and then it was gone. There was silence, as though everyone was trying to be sure that it had stopped. Dr. Ice Cream cleared her throat. Jake had been holding onto her cone very tightly, his eyes shut. He opened one eye, then the other, then realized his face was buried in the doctor's cream.

"Oh, eh, ah heh heh, sorry bout that." He said, letting her go.

"Mmmhm." Dr. Ice Cream said before walking away to tend to her patients.

While everyone else was trying to gather themselves, Susan burst from the room with the baby in her arms. She was howling her panicked babble, her eyes darting this way and that, looking for an escape. Finn sensed her anxiety and knew that she would do something crazy if she wasn't calmed down. With difficulty, he unstuck himself from PB and ran to Susan.

"Susan! Calm down! " He called. She didn't seem to hear him. Cinnamon Bun was running for his life, unaware that the earthquake was over. Susan wacked him when he tripped into her by accident. Jake quickly caught Cinnamon Bun, who upin release said, "Thanks" then continued running for his life.

Finn managed to get Susan back into the hospital room, then turned to his friends.

"What's going on with the earthquakes, PB?" Finn asked, shutting the door. Princess Bubblegum was staring out the window, looking at the destruction the last quake had caused. Small clusters of candy people were starting to clean up here and there. She didn't know what was wrong. Everything underground was fine, it wasn't the planet shifting about to get comfortable or releasing pressure. But still there were earthquakes. Why?

"Let's go to my Lab of Science." PB offered.


	3. Chapter 3: Shock

Chapter 3: Shock

Finn and Jake followed the princess back to the castle, pausing to help a fellow citizen lift a lampost back up or lick and stick an arm or an eye ball back on.

Out of the three, Jake seemed most anxious to get to the castle. He hadn't seen Lady Rainicorn since the morning and there had been at least three earthquakes since then. In her condition, it seemed irresponsible to be away from her at all, but she and Finn insisted that he didn't need to be their 24/7. Jake still hadn't quite wrapped his head around the fact that he was going to be a dad.

When they arrived at the lab, Princess Bubblegum immediately went to her largest and most complex looking piece of machinery. It was quite impressive and Finn watched intently to see what 'science' it would perform. To his surprise, PB opened the front and pulled out a pitcher of water, poured herself a glass and then put it back. It was just a refrigerator.

After taking a deep gulp, Princess Bubblegum set the half empty glass down on the ground and stared at it. Finn could only wait. As the seconds ticked by, he glanced about, noticing that Jake wasn't with them. He waited several moments longer, but PB continued to stare at the glass.

"Um...What are you doing?" He asked.

"Sh." She said. Finn stayed quiet. Not long after that, she snatched the glass up.

"It's just as I thought. There are no earthquakes!" She huffed, going to a bookshelf and pulling down several heavy books. A closet in the corner suddenly slammed open, causing Finn to jump. Marceline the Vampire Queen drifted out.

"No earthquakes? Bonnibel, I think that sugar is going to your head. I can feel the shaking without even being on the ground." She said, doing a lazy somersault in the air. PB didn't even look up, as though Marceline hiding in her lab wasn't an unusual occurrence. After giving it some thought, Finn decided that it probably wasn't.

"Exactly! If you're floating in the air, you wouldn't feel an earthquake." Princess Bubblegum suddenly exclaimed, turning around so fast that the water in glass she held sloshed about. Marceline and Finn exchanged glances. It made sense but it still didn't explain the tremors. They waited for her to elaborate.

"So...this is a dream?" Finn asked a little awkwardly, because if it was, it wouldn't be the strangest dream he had ever had. PB looked down.

"No, Finn. It's not. It doesn't make any sense." She muttered, turning back to her ancient volumes. Marceline floated behind him and pinched his cheeks.

"Can't you tell when you're in a dream or not? There hasn't even been any monsters or other cool things like that. Unless your dreams are boring." She said thoughfully. Jake appeared in the room.

"Lady's fine. Oh hey Marceline. Has Peebles figure out what's rocking our world so hardcore?" he asked, strutting over to Finn. A frustrated grunt from Princess Bubblegum answered his question.

"Ooooooooooh...kay. D'ya wanna get outta here Finn? Maybe we should go help the candy people clean up or something." Jake said.

"Yeah. I wonder if they got Susan to cooperate..." Finn answered, starting to follow Jake. An angry hiss from Marceline caused the hair on the back of his neck to rise up, then he felt that deep rumbling again.

"Here it comes again!" Princess Bubblegum cried out unecessarily. Finn and Jake braced themselves against the wall. This time, the shaky seemed more violent, like the air itself was shuddering. In fact, you could see a blurred spot forming in the middle of the room. The quavering continued to intensify, Finn felt his teeth chattering and his brain rattling in his skull.

He thought he heard PB scream just as a flash of bright light stunned them all. Had the trembling stopped? Had they died because their innards aren't meant to be stirred up maraca style?

Trying to rub the blindness from his eyes, they refocused in time to see a gaping hole open out of thin air. A bunch of people came tripping out in a fashion that reminded Finn of the last time he threw up. It seemed like the content of his stomach seemed to push and shove it's way out his mouth.

The last person came through much more like a bullet shooting out. They landed on their feet but too much momentum forced them forward, right into Finn.

"Whoops, sorry about that." She said. She stood upright and straightened her hat with bunny ears, flipping blond hair out of her eyes. It was a wild awesome ride under the circumstances. Then she noticed the boy she had bumped into was staring at her in a strange way. At first she was indignant, then she realize he wasn't like any boy she had ever seen before. He looked...familiar.

Finn seemed to have lost all ability to think. Or close his mouth.


	4. Chapter 4: Insight

Chapter 4: Insight

Jake groggily sat up, apparently having blacked out during the latest tremor.

"Urgh, what happened?" He groaned woozily. Finn wasn't exactly sure what to say.

"Um...a giant hole appeared out of no where and barfed out a buttload of people." He answered. Jake gaped a little, first at Finn, then at the suddenly full room. He was pretty sure there wasn't that many people there when he came in.

Finn was still staring at the girl that had run into him. She seemed to be unable to look away either but still seemed to be uncomfortable.

"Um...hi. I'm Fionna." She said, trying to cut through the awkward air.

"I'm Finn." Finn answered. Neither of them said anything more. Jake was still gaping at all the people. They seemed to be unconscience or at least, he hoped they were. He thought he saw something glow at the bottom of a sizable pile of bodies.

"What's that smell?" PB murmured, rousing from her own unconsciousness. Finn then noticed it too. It was sweet like someone baking cookies. Then it grew stronger and smoky. The sizable pile of bodies suddenly exploded.

"GET OFF!" roared the gigantic flame monster in the middle of the room. Finn thought it was Flame Princess for a moment, wondering when she got there. Everyone was scurrying away, a couple seemed to have been burned. He took a heroic step forward with intentions to help, knowing that Flame Princess would get into trouble if she hurt anyone. Then Fionna swooped past him.

"Flame Prince! Calm down before you hurt someone!" She yelled at the flaming creature. Flame PRINCE? Finn watched as fire died down, shrinking to the form of a thin, glowing boy with angry orange hair. He could almost be Flame Princess, except that he wasn't a she.

Finn didn't know what to say. Then he noticed the others getting up, brushing off, looking around at their surroundings, talking to one another.

"I totally knew we were going to live. I mean, for a second, I was, like, dude, if this doesn't work, I'll totally save everyone, what do you think these muscles are for anyway?" Said a rather large purple cloud that resembled Lumpy Space Princess except for a few straggly hairs on its upper lip.

"Sure. That's why you were holding onto Sampson screaming 'OH GLOB, OH GLOB! WE'RE ALL GOING TO DIE!' " teased a pale, lanky guy who was floating a foot off the ground. On his neck was two red dots like the ones Marceline had. Behind them, a massive figure sat up. Shaggy blonde hair poked out from under his cat hat.

All of these people were familiar, but Finn was sure he hadn't met them before. He didn't really start to understand it until he saw the pink guy. Pink clothes, pink skin, pink hair on top of which sat a crown. It was Princess Bubblegum, but a guy.

Once he knew this, Finn realized that they all were guy versions of the girls he knew. And if there were guy versions of the girls, there had to be girl versions of the guys. Finn looked at Fionna, who was talking to Flame Prince. He was looking at himself as a girl.


	5. Chapter 5: Missing

Chapter 5: Missing

Prince Gumball got to his feet, brushing himself off, taking a moment to be relieved that he was on solid ground again, then looked around at his friends and subjects. While he was glad his equation to open the singularity worked finally and that they had made it, he couldn't help but feel sad that this was all that was left of his world.

"Who are you?" a voice demanded. He turned to face a floating vampire girl with a scowl that was identical to Marshal Lee's. She had lots of silky black hair and a slender frame. Prince Gumball impulsively turned on the charm.

"I am Prince Gumball. Who might you be?" He asked with a slight bow. Princess Bubblegum suddenly snapped out of her drowsiness.

"What? You're who?" She demanded, staggering to her feet and stumbling to where Marceline and PG were.

"I'm you. From another universe. Prince Gumball of the Candy Kingdom in the Land of Aaa. Well, I was." He said, looking down. Marceline and Princess Bubblegum exchanged looks.

"Why are you here?" PB asked.

"Ah, yes. I suppose I could have sent some sort of warning but-" Prince Gumball began apologetically, but Marshall Lee cut in.

"-We were a little busy trying to stay alive. Hi, Marshall Lee, Vampire King. Hope we're not imposing, but our universe just collapsed." He said bluntly. Prince Gumball scowled at him then turned back to the girls.

"Yes... What he said." He said glumly when he realized he couldn't explain it any better himself. They didn't say anything and there was nothing but the noise of the refugees talking about what they had just escaped. The wheels in Princess Bubblegum's head began turning again.

"Is that why we were experiencing so many tremors? That was you trying to open a wormhole between our universes?" she asked.

"We did try several times, but I didn't think it would cause any disturbances, can you explain these tremors? Do you have any technical readouts?" Prince Gumball asked. Sensing that the conversation was quickly going to 'science' Marceline turned to Marshall. They seemed to size one another up. After a while, Marceline spoke first.

"Do you like music?" she asked.

"Yes." Marshall answered.

"Rock?" Marceline inquired further.

"What other kind of music is worth listening to?" He asked. Marceline smirked, meriting one from Marshall as well.

Finn had been watching this exchange between his friends, wondering how they could accept this so easily. He had seen a lot of crazy stuff before but this was beyond all of it. Suddenly Jake spoke up.

"Hey, don't I have a different universe me?" He asked loudly after surveying the other doubles. Fionna suddenly looked up, realizing that her best friend was missing. She scanned the room, looking for a familiar little fluffball, her heart starting to sink when she realized that Cake was no where to be seen.

"She and Lord Monochromicorn were trying to get the Ice Queen to go through the portal." Peppermint Maid murmured, as though hearing Fionna's thoughts. She swallowed hard. It was too late to save them, crying about wouldn't help the situation now.

Seeing her so sad, Finn felt a drawn to Fionna. He approached her a little awkwardly.

"I'm sorry you lost your friend." he said, unsure of what else to say. Fionna looked up at him.

"Cake wasn't just my friend, she was my sis. We've always been together. She was going to have a..." Fionna said, her throat suddenly seizing when she thought of the babies Cake would never have. She buried her face in her hands so no one would see her struggling not to cry. Hesitantly, Finn put a hand on her shoulder in the hope to offer some comfort.

To the side, Jake was feeling stupid for being such a loud mouth. Then he thought of Lady. After the last violent earthquake, he wasn't sure how it affected the rest of the castle. He quickly sprinted up the steps toward Lady's room.

"Listen up, attention people, ATTENTION!" Princess Bubblegum called. The chatter quieted. She and Prince Gumball stood side by side, their faces grim. PB was the one to speak.

"The Land of Ooo welcomes the refugees from Aaa, but after studying our science readouts, it seems that our universe is on it's way to collapsing just like yours."


End file.
